PHP

<?php
   session_start();

   if(isset($_POST['logged_in') {

      $user_name = mysqli_real_escape_string($db,$_POST['username']);
      $user_password = mysqli_real_escape_string($db,$_POST['password']);

      $sql = "SELECT * FROM users WHERE username = '$user_name' and password = '$user_password'";
      $result = mysqli_query($db,$sql);
      $row = mysqli_fetch_array($result,MYSQLI_ASSOC);
      $active = $row['active'];

      $count = mysqli_num_rows($result);


      if($count == 1) {
         session_register("user_name");
         $_SESSION['login_user'] = $user_name;
        }
    }
?>